There is known an autonomous travel system that connects autonomously-traveling haulage vehicles (hereinafter called “unmanned dump trucks”), which can perform autonomous traveling without operators onboard, for communications with a traffic control system via a wireless communication network in an surface mine or the like. In a mining environment, unmanned dump trucks, graders and bulldozers are operated together with vehicles driven by operators (hereinafter called “manned vehicles”) such as light vehicles (for supervision or transportation of employees, etc.) and sprinkler vehicles. The traveling positions and operation conditions of these unmanned dump trucks, graders, bulldozers and manned vehicles are controlled by an autonomous travel system, and are subjected to traffic control on the basis of map data, which have been created beforehand, and the traveling positions so that these vehicles do not interfere with each other.
On a travel road, an obstacle other than those to be subjected to traffic control, such as a fallen rock or an object fallen on the travel road, may exist. As a technology for avoiding such an obstacle, Patent Document 1, for example, discloses the following technology: “To perform precise cooperative control between automatic brake control and steering assist control, the automatic brake control is performed if the relative position of an obstacle, which exists ahead of an own vehicle, to the own vehicle as detected by a relative position detecting means for detecting the relative positions of the own vehicle and the obstacle is in a first region ahead of the own vehicle, and the steering assist control is performed if the detected relative position of the obstacle exists in a second region that is located outside the first region and is broad in a vehicle width direction” (see the Abstract).